Pleione limprichtii hardiness

[plantzzzzz]

Fraser's Thimble Farms - Cypripedium, lady slipper, Hardy Orchids, Pleione, Bletilla

This Canadian nursery sells Pleione Limprichitii, and claims that it is hardy to -20C.

However, every other site on the culture of this orchid says that it cannot handle hard freezes.

Does anyone else have experience growing this plant outdoors in cold climates?

I can do a dry -20C min, but here in zone 5b it will definitely freeze.